Revert "Make Mushroom Grove/Lit Mushroom Grove behave like forests, move-wise"

Requested by Wintermute: <http://r.wesnoth.org/p573664>

This reverts commit 753ddabc4c.

changelog

@@ -299,8 +299,6 @@ Version 1.13.0-dev:
    * Add [has_ally], [has_enemy] to work around issues reported here: http://forums.wesnoth.org/viewtopic.php?f=21&t=40702
      In a side_filter, [has_ally] and [has_enemy] are corrected / simplified versions of [allied_with] / [enemy_of], this
      is an extension of the bugfixes for [filter_vision].
-   * Mushroom Grove and Lit Mushroom Grove now favor the terrain with the worst
-     movement costs between the base and overlay (bug #21971).
    * Fix [side] share_view/maps always beeing false for non-first levels in mp campaigns
    * Fixes start-of-scenario multiplaer saves (#22068)
    * Fix bug wherein "lobby sounds" advanced preference didn't do anything for the normal (GUI 1) lobby.

data/core/terrain.cfg

@@ -845,8 +845,7 @@ Most units receive 20 to 40% defense in sand."
     name= _ "Mushroom Grove"
     editor_name= _ "Mushroom Grove"
     string=^Uf
-    aliasof=_bas,Uft
-    mvt_alias=-,_bas,Uft
+    aliasof=Uft
     default_base=Uu
     editor_group=cave, forest
 [/terrain_type]
@@ -858,8 +857,7 @@ Most units receive 20 to 40% defense in sand."
     editor_name= _ "Lit Mushroom Grove"
     string=^Ufi
     default_base=Uu
-    aliasof=_bas,Uft
-    mvt_alias=-,_bas,Uft
+    aliasof=Uft
     light=25
     editor_group=cave
 [/terrain_type]

players_changelog

@@ -78,8 +78,6 @@ Version 1.13.0-dev:
    * Fix unit move continuation if enemy discovered (#21372)
    * Support for total conversions, so called "cores". 
    * Partial moves now able to be continued properly in whiteboard (#22231)
-   * Mushroom Grove and Lit Mushroom Grove now favor the terrain with the worst
-     movement costs between the base and overlay (bug #21971).
    * Fix bug wherein "lobby sounds" advanced preference didn't do anything for the default lobby.
    * Fix bug wherein dbus notifications did not have a wesnoth icon
    * Fix bug wherein chat history synopses weren't working right in the dbus notifications